Patent documents EP0052151 and WO2007031330 describe similar containers, both made of a flexible material and in which there are distinguished, in the normal open position, two facing side walls and an upper base. The described containers furthermore comprise a lower base, similar in the two containers, formed by means of folding towards the interior of the container a portion of laminar band along a longitudinal fold line, which confers to the lower base an inverted “V” shape known in the art.
To date, providing the upper base of a container with these features of a rigid spout, which can be plugged by means of a cap or similar element, significantly altered the method and the machine necessary for continuously manufacturing the containers. This is so because in order to place the spouts in a central area of the upper base and fix it to the material forming said upper base it is necessary to individualize the container from the continuous laminar band or bands from which the containers are obtained, the end of the container being opposite the upper base that is still unclosed, for the purpose of being able to introduce in the container being manufactured, through its open lower base or bottom, the means necessary for performing the attachment by heat welding between the spout and the sheet portion. For this operation, at least a welding jaw and a welding counter-jaw are required, one of which acts from the exterior of the container and the other one of which acts from its interior, there being arranged between them, in a compressed manner, an essentially planar part of the spout and the portion of the upper base intended to be inseparably and tightly attached to the spout.
This way of operating is not applicable to any of the processes described in the aforementioned documents, in which the bottom of the container, and in this case the lower base, is always closed before individualizing the containers.
It is, therefore, a first objective of the invention to disclose an alternative method for continuously manufacturing and filling containers by means of which it is possible to obtain containers such as those described in WO2007031330, but also, without it being necessary for that purpose to significantly alter the means for putting it into practice, containers provided in their upper base with a spout suitable for extracting the contained product from the container.
It is another objective of the present invention that the method is suitable for obtaining the containers from a single initial laminar band if desired.
It is also an objective of the invention that the method allows obtaining containers the upper base of which lacks, at least along part of its contour of attachment with the side walls, heat-welded rims.
In addition, by means of the known processes for obtaining containers with an upper base, the sheet portion forming the mentioned upper base is folded over itself and towards the interior of the container, forming a portion folded in a general V shape the orthogonal edges of which are applied against the inner surface of the sheet portions forming the side walls, said edges being attached by means of respective triangular welds to said side walls which, furthermore, are also attached to one another. Thus, once the container is full, the upper base forms a cover with a general dome shape, having two opposite ends slightly sunken between the upper portions of the side walls of the container, which remain upright due to the effect of the aforementioned triangular welds and the attachment of the side walls, with orthogonal edges, along the entire length thereof.
These sunken ends of the upper base and the side walls which are raised on both sides of the container determine respective cavities in which dirt is housed during the periods of storage, transport and emptying of the containers.
Another objective of the present invention is that the method is suitable for obtaining an alternative container, obtainable from a single flexible sheet, which prevents the aforementioned drawback and at the same time improves the mechanical properties of the container once it is full and during the manoeuvres of opening the cap or closing the spout. In order to open the container, it is occasionally necessary to firmly hold the container while a turning movement is applied to the closure element or cap of the spout, especially when it is coupled to the body of the spout by screwing, and this turning movement can cause, by reaction, the container to have a tendency to be deformed by torsion around its vertical axis.